Drawing instruments



July 38, 39$? ER 3,331,133

DRAWING INSTRUMENTS Filed June 13, 1966 4 Sheets-Sheet 1 I nvenlor Jufiy 3, 11967 A. A. GRIMMEZR DRAWING INSTRUMENTS 4 Sheets-Sheet 2 Filed June 13, 1966 Inventor A A GRMMER B a \M NJM 2 5L5 Attorneys July 18, 1967 A. A. GRIMMER 3,331,133

DRAWING INSTRUMENTS Filed June 15, 1966 4 Sheets-Sheet 3 km \A i 1 l x I .T w U 1 L213, Inventor hi II A. A GRMMER HI I B I I Q M1%% 13, 1957 A. A. GRIMMER DRAWING INSTRUMENTS 4 Sheets-Sheet 4.

Filed June 13, 1966 I lnvenlor A.A.GR\MMER A ltorey s United States Patent 3,331,133 DRAG HVSTRUMENTS Archibald Albert Grimmer, 103 The Grove, Ealing, London, England Filed June 13, 1966, Ser. No. 557,116 Claims priority, application Great Britain, June 17, 1965, 25,752/65 Claims. (Cl. 33-31) The present invention relates to drawing instruments by means of which families of ellipses, ovals, or like figures, dimensions may be developed. Such instruments will hereinafter be generically designated ellipsographs.

The invention is particularly concerned with an ellipsograph of the type comprising a first member which is guided so as to be movable in the direction of one axis, for example, the minor axis of an ellipse or like figure to be developed, and a second member which is guided so as to be movable in the direction of another axis, for example, the major axis, of the figure, the first and second members being coupled together by, or forming part of, a link which, upon simultaneous movement of the two members, is adapted to move a marking or tracing implement, such as a pen or pencil, along the contour of the figure. Such an ellipsograph will hereinafter be referred to as an ellipsograph of the type specified.

An ellipsograph of the type specified is capable of developing one half of an ellipse or like figure as a single or continuous operation, but before the second half can be developed, it is necessary to bodily reverse the position of the ellipsograph on the drawing surface, necessitating accurate re-alignment of the ellipsograph with both axes of the partly developed figure.

According to the present invention, an ellipsograph of the type specified is provided with an element capable of being urged into engagement with a surface on which the oval, ellipse or like figure is to be developed, when the ellipsograph is located thereon, at a position corresponding to the intersection of the axes of the figure, to permit the ellopsograph to be bodily rotated about said intersection.

When one half of the figure, for example, an ellipse, has been traced out, the element, which may be of a retractable pin carried by the second member, is urged against or into the drawing surface and the ellipsograph is swung bodily around the point of contact of the element with the intersection until the ellipsograph is realigned with the axes. The element is then released and the second half of the ellipse may then be drawn. By reversing the ellipsograph whilst positively retaining it aligned with the intersection, accurate and rapid re-alignment of the ellipsograph may be achieved.

In order that the invention may be more readily understood, one embodiment thereof will now be described with reference to the accompanying drawings, in which:

FIGURE 1 is an exploded perspective view of the ellipsograph;

FIGURE 2 is a plan view of the assembled ellipsograph showing the positions of the components both before and during the development of the first half of an ellipse;

FIGURE 3 is a longitudinal section on the line 33 of FIGURE 2, on an enlarged scale, in the condition in which the link is parallel to the major axis of the ellipse being drawn, with part of the link broken away, and with the components adjusted to develop an ellipse of smaller dimensions than that shown in FIGURE 2;

FIGURE 4 is a longitudinal section through one of the outer base parts; and

FIGURE 5 is a perspective View of the assembled ellipsograph.

3,31,133 Patented July 18, 1967 Referring to the drawings, the ellipsograph comprises a two part central base part 1 and a pair of outer base parts 2, all of which may be made, for example, moulded from a synthetic plastics material such as a transparent or opaque hard nylon. Each of the parts 1 and 2 has a downwardly opening, longitudinal channel 1a, 2a respectively, spaced from an edge of its associated part by a depending rib 1b, 2b respectively, of reduced depth. Secured rigidly to the undersurface of the ribs 1b and 211, for example, by rivets 3, is a longitudinal guide bar 4, which may be made from metal strip, and which as will be seen from FIGURE 3, is raised above the undersurfaces of the base parts 1 and 2, and projects on opposite sides of the ribs 1b and 2b. Upstanding knurled projections 5 may be provided, secured by rivets 6 to the base parts 2 to facilitate handling of the ellipsograph, and anti-slip elements may be provided on the underside of these base parts 2, for example, rubber or glass paper pads or washers 7 to minimise the possibility of accidental bodily movement of the base parts during use of the instrument.

A first member comprising a slide 8, which may also be made from nylon, is slidable along and beneath the guide bar 4, through and between the base parts, and is located on the guide bar 4 by means of an upstanding grooved portion 8a which engages around the longitudinal edge of the guide bar 4 projecting into the channels 1a and 2a. The slide 8 is pivotally connected, for example, by a rivet 9, to an arcuate end 10a of a rigid lever or link 10 formed, for example bent up from a metal wire or rod. As will be apparent from FIGURE 3, the said end 10a is undercut at 1% to engage the opposite longitudinal edge of the guide bar 4 and retain the slide 8 assembled to the guide bar 4.

The two components of the central base part 1 are both formed, in their opposed surfaces, with a transverse groove 10, and a metal arm 11 is retained in this transverse groove lc when the two components are assembled together, for example, by the rivets 3 and also the rivets 15, so as to be slidable in a direction normal to that of the slide 8. This arm 11, in its portion normally located in the base part 1, is formed with an aperture 11a through which a hair line 1d (see FIGURE 2), engraved on the underside of the transparent base part 1, may be viewed. The outer end of the sliding arm 11 is pivotally connected to the link 10' by a second member which includes a first block 12 and a knurled finger nut 13. By tightening the nut 13, the link 10 is clamped between the block 12 and a washer 14, although the arm 11 is still free to pivot about the nut 13, whilst, by loosening the nut 13, the link 10 may be slide relative to the block 12 to adjust the spacing between the pivotal connections of the link 10 to the slide 8 land to the arm 11 respectively.

The nut 13 and block 12 incorporate an axial stepped passage 15 (see FIGURE 3) containing a slidable pin 16 having a point at its lower end. The upper end of the pin 16 carries a button 17 which is located in, and projects out of, the upper surface of the nut 13. A compression spring 18 surrounds the upper end of the pin 16 and is compressed between the opposed surfaces of the button 17 and nut 13, so that it normally urges the pin into the retracted position shown in FIGURE 3. The amount of retractive movement of the pin 16 is restricted, and the lower end of the pin is steadied, by a sleeve 19 of nylon or other suitable material which is pressed onto the pin and is slidable therewith within the enlarged lower end of the passage 15.

A second block 20 is also mounted on the link 10, and, together with a washer 21 and arm 22, may be clamped in a required position along the link 10, in a similar manner to the block 12 by tightening a knurled finger nut 23. The arm 22 extends along the link 10, and is prevented from swinging relative thereto about the nut 23 by a downwardly depending finger 22a which engages between the two limbs of the link 10. The arm 22 is also provided with a bore 22b to receive and locate a marking implement such as a pencil point or, as shown in FIG- URES 3 and 5, a pen 24 of the stylus type, which is detachably held in place by a locking screw 25.

Both of the blocks 20 and 12, are provided on both sides of their side faces with graduations 20a and 12a respectively, corresponding respectively to the positions of the axes of the bore 22b and the passage 15.

To use the instrument, it is first adjusted dependent upon the size and angle of the ellipse to be drawn. In this respect, the minor and major axes 26 and 27 respectively (see FIGURES 2 and 5) are first drawn on a drawing surface, for example, paper and their maximum dimensions marked off. The instrument is then placed on the surface, with the link disposed parallel to and engaging the edge of the guide bar 4 (position A in FIGURE 2) is then placed over these axes, and the hair line 10. on the base part 1 is viewed through the aperture 11a in the arm 11, and accurately aligned with the major axis 27. At the same time, the graduations 12a and 200! on the blocks 12 and 20 are aligned with the minor axis 26. Then, whilst the base part 1 is firmly held on the drawing surface, the link 10, by gripping the nut 23, is swung to position B shown in FIGURE 2 in which it is normal to the guide bar 4, and after loosening the nut 23, the block 20 is adjusted along the link 10 until the tip of the pen 24 coincides with the maximum dimension of the major axis 27, whereafter the nut 23 is re-tightened. The link 10 is then returned to position A and, with the nut 13 loosened, the link 10 is adjusted relative to the block 20 to bring the tip of the pen 24 into coincedence with the maximum dimension of the minor axis 26, and then the nut 13 is i e-tightened.

Having thus set the instrument to the required minor and major dimensions of the ellipse, the link 10 is swung from position A, with the pen 24 in engagement with the drawing surface, in the direction of the arrow, through position Bin which the link 10 is normal to the guide bar 4 and the arm 11 is withdrawn partly from the base part 1, to a position (not shown) in which. the link 10 projects to the right, opposite to position A, whilst the base parts 1 and 2 are firmly manually retained on the drawing surface. The pen 24 follows the elliptical path shown by virtue of the fact that the pivotal connection 9 of the slide 8 to the link 10* is constrained to move only along the minor axis, whilst the pivotal connection of the link 10 to the arm 11 is constrained to move only along the major axis.

At this stage, only one half of the ellipse has been drawn, and in order to draw the other half it is necessary to reverse the position of the ellipsograph. This is achieved by depressing the button 17, Whilst still retaining the link 10 in its position directly opposite to position A, so that the point of the pin 16 penetrates the drawing surface at the intersection of the major and minor axes. The ellipsograph is then bodily swung about the axis of the pin around the intersection through 180 until the longitudinal edge of the guide bar 4 is parallel to, but on the opposite side of the minor axis 26, and the graduations 12a and 20a are realigned with this axis. The button 17 is then released to retract the pin, whereafter the second half of the ellipse is drawn in the same manner as the first half. Since the arm 22 spaces the pen 24 away from the block 20, which rests on the drawing surface during this operation, there is no risk of smudging or blotting of the ink from the pen 24 by the block 20.

By swinging the ellipsograph about the pin 16, the reverasl and consequent re-alignment of the ellipsograph may be accurately, simply and rapidly achieved. More- 4 over, by restraining the slide 8 to move only along the guide bar 4, instead of merely resting the end of the link 10 against the latter, manipulation of the instrument is considerably facilitated.

By adjusting the positions of the blocks 12 and 20 relative to each other along the link 10, and relative to the pivotal connection 9 of the link 10 to the slide 8, families of differently dimensioned ovals, ellipses or like figures may be developed.

It will be understood that various modifications may be made without departing from the scope of the present invention as defined in the appended claims. In this respect, although it is advantageous to employ the slide 8 since it positively restrains the link 10, ensuring that the pivotal connection therebetween moves only. along the minor axis, the slide 8 may be omitted, and the end of the link may simply abut and slide against the edge of the guide bar. In this event, to reduce wear, a roller may be rotatably mounted at the inner end of the link. The roller or end of the link may be manually urged against the guide bar during use, or may be urged thereagainst by means of a light tension spring connected between the base part and the arm 11, which. tends to retract the arm into the base part. It is also possible to use a roller in conjunction with the slide 8, for example, by replacing the undercut inner end 10a of the link by a roller.

The outer base parts 2 may be omitted, or may be joined to the central base part 1, to form a single rulerlike base. In this event, the guide bar 4 may be replaced by a longitudinal flange depending from and integral with the base, around which the slide fits. Alternatively, the base may incorporate a dove-tail or similar undercut channel in its underside in which a correspondingly shaped slide may fit. The ruler-like base, or the guide bar may be calibrated in units of length, as may also be the link 10, to enable dimensions of the major and minor axes to be read otf or, facilitate adjustment of the blocks 12 and 20 to the desired dimensions.

The pin 16 may be replaced by other elements capable of locating the instrument during bodily movement about the intersection of the major and minor axes. Additional bores may be provided in the arm 22 in line with the bore 22b to accommodate marking implements of differing sizes.

I claim:

1. An ellipsograph of the type specified, provided with i a first member movable in the direction of one axis of a figure to be developed, a second member movable in the direction of another axis of the figure to be developed, an elongated link, first and second connecting means respectively pivotally connecting said first and second members to said link at spaced positions along the link, a third member carried by the link,.for locating a marking implement, and spaced along saidlink from said first connecting means by said second connecting means whereby, upon simultaneous movement of said first and second members a marking implement, when located bysaid third member, is moved by said link along the contour of the figure to be developed, a retractable element capable of being manually urged into engagement with a surface on which the figure is to be developed, when the ellipsograph is located thereon, at a position corresponding to the intersection of the axes of the figure, to permit the ellipsograph to be bodily rotated about the intersection, said element being mounted for bodily movement with said second member, and means adapted normally to retract said element from engagement with said surface.

2. An ellipsograph as claimed in claim 1, including a base which is adapted to. restrain the first and second members to move onlyin the directions of the said relative to said first and second connecting means, and

in which said retractable element comprises a pin.

3. An ellipsograph as claimed in claim 2 wherein the first member comprises a slide engagable with a correspondingly shaped surface associated with the base, the slide being pivotally connected by said first connecting means to one end of the link.

4. An ellipsograph as claimed in claim 3, wherein said correspondingly shaped surface is defined by a longitudinal guide bar carried by the base, said slide being engagable around said bar, wherein the second member comprises an arm slidable in a channel in the base at right angles to the guide bar, and wherein one or more anti-slip elements are provided on the underside of the base.

6 References Cited UNITED STATES PATENTS 442,252 2/1890 Rawson 33-31 2,777,199 1/1957 Neighek 33-31 X 2,879,596 3/ 1959 Kroenlein 33-31 FOREIGN PATENTS 112,764 4/ 1929 Austria.

80,177 3/1895 Germany. 597,799 2/ 1948 Great Britain.

LEONARD FORMAN, Primary Examiner. H. N. HAROIAN, Assistant Examiner. 

1. AN ELLISOGRAPH OF THE TYPE SPECIFIED, PROVIDED WITH A FIRST MEMBER MOVABLE IN THE DIRECTION OF ONE AXIS OF A FIGURE TO BE DEVELOPED, A SECOND MEMBER MOVABLE IN THE DIRECTION OF ANOTHER AXIS OF THE FIGURE TO BE DEVELOPED, AN ELONGATED LINK, FIRST AND SECOND CONNECTING MEANS RESPECTIVELY PIVOTALLY CONNECTING SAID FIRST AND SECOND MEMBERS TO SAID LINK AT SPACED POSITIONS ALONG THE LINK, A THIRD MEMBER CARRIED BY THE LINK, FOR LOCATING A MARKING IMPLEMENT, AND SPACED ALONG SAID LINK FROM SAID FIRST CONNECTING MEANS BY SAID SECOND CONNECTING MEANS WHEREBY, UPON SIMULTANEOUS MOVEMENT OF SAID FIRST AND SECOND MEMBERS A MARKING IMPLEMENT, WHEN LOCATED BY SAID THIRD MEMBER, IS MOVED BY SAID LINK ALONG THE CONTOUR OF THE FIGURE TO BE DEVELOPED, A RETRACTABLE ELEMENT CAPABLE OF BEING MANUALLY URGED INTO ENGAGEMENT WITH A SURFACE ON WHICH THE FIGURE IS TO BE DEVELOPED, WHEN THE ELLIPSOGRAPH IS LOCATED THEREON, AT A POSITION CORRESPONDING TO THE INTERSECTION OF THE AXES OF THE FIGURE, TO PERMIT THE ELLIPSOGRAPH TO BE BODILY ROTATED ABOUT THE INTERSECTION, SAID ELEMENT BEING MOUNTED FOR BODILY MOVEMENT WITH SAID SECOND MEMBER, AND MEANS ADAPTED NORMALLY TO RETRACT SAID ELEMENT FROM ENGAGEMENT WITH SAID SURFACE. 